Curable composition

ABSTRACT

A curable composition and use thereof are provided. The exemplary curable composition can show excellent processability and workability. Also, the curable composition can have a high refractive index before or after curing. The composition has low moisture permeability before or after curing and shows excellent crack resistance, thermal shock resistance, adhesive property and hardness. In addition, the composition does not cause color change such as whitening, under a high-temperature or high-humidity condition, and does not exhibit stickiness on a surface thereof. The curable composition may be used as an adhesive material or as an encapsulation material for semiconductor devices such as an LED, a CCD, a photo coupler, or a photovoltaic cell.

TECHNICAL FIELD

The present invention relates to a curable composition and use thereof.

BACKGROUND ART

As light emitting diodes (LEDs), particularly blue or ultraviolet (UV) LEDs having an emission wavelength of approximately 250 nm to 550 nm, high-brightness products using a compound semiconductor made of a GaN-based compound such as GaN, GaAlN, InGaN or InAlGaN have been developed. Also, it is possible to form a high-definition full-color image using a technique of combining the above-described blue LEDs with red and green LEDs. For example, there is a known technique of manufacturing a white LED by combining a blue or UV LED with a fluorescent material. Such a white LED is expected to be increasingly used for backlights of liquid crystal display devices (LCDs) or general lighting.

An epoxy resin having a high adhesive property and excellent dynamic durability has been widely used as an LED encapsulation material. However, the epoxy resin has problems in that it has low transmittance with respect to light ranging from blue to UV wavelength ranges, and also shows poor light resistance. Accordingly, for example, Patent Documents 1 to 3 disclose techniques proposed to solve the above-mentioned problems. However, the encapsulation materials as described in the above-mentioned patent documents have a problem in that they still show poor light resistance.

Meanwhile, a silicone resin has been known as a material having excellent light resistance at a low wavelength range. However, the silicone resin has problems in that it shows low heat resistance and has a sticky surface after a curing process. To effectively employ the silicone resin as an encapsulation material for LEDs, it is also necessary to ensure characteristics such as a high-refractive index characteristic, crack resistance, surface hardness, adhesive strength and thermal shock resistance.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Patent Laid-open Publication No.     Hei11-274571 -   Patent Document 2: Japanese Patent Laid-open Publication No.     2001-196151 -   Patent Document 3: Japanese Patent Laid-open Publication No.     2002-226551

DISCLOSURE Technical Problem

The present invention is directed to providing a curable composition and use thereof.

Technical Solution

One aspect of the present invention provides a curable composition. The curable composition according to one exemplary embodiment may include a mixture of a siloxane oligomeric compound and a linear polysiloxane containing an alkenyl group bound to a silicon atom. Also, the curable composition may include a silicon compound containing a hydrogen atom bound to a silicon atom (hereinafter simply referred to as a “silicon compound”). According to one exemplary embodiment, the curable composition may be a composition that is cured by a hydrosilylation reaction.

In this specification, the term “unit M” may refer to a siloxane unit forming a polysiloxane or a siloxane oligomeric compound, that is, a monofunctional siloxane unit which is generally represented by the expression (R₃SiO_(1/2)) known in the related art, the term “unit D” may refer to a siloxane unit forming a polysiloxane or a siloxane oligomeric compound, that is, a difunctional siloxane unit which is generally represented by the expression (R₂SiO_(2/2)) known in the related art, the term “unit T” may refer to a siloxane unit forming a polysiloxane or a siloxane oligomeric compound, that is, a trifunctional siloxane unit which is generally represented by the expression (RSiO_(3/2)) known in the related art, and the term “unit Q” may refer to a siloxane unit forming a polysiloxane or a siloxane oligomeric compound, that is, a tetrafunctional siloxane unit which is generally represented by the expression (SiO_(4/2)) known in the related art. In the units M, D and T, specific kinds of the substituent “R” binding to a silicon atom will be described later.

According to one exemplary embodiment, the linear polysiloxane may include units represented by the following Formulas 1 and 2. Each of the units of the following Formulas 1 and 2 is a unit D forming a linear polysiloxane. As such, a mole number of the unit of Formula 1 may be, for example, 1 to 5 times, or 1.5 to 3 times higher than that of the unit of Formula 2. Within this mole number range, the curable composition may show a high refractive index while maintaining proper viscosity.

R^(a)R^(b)SiO_(2/2)  [Formula 1]

R^(c)R^(d)SiO_(2/2)  [Formula 2]

In Formulas 1 and 2, R^(a) and R^(b) are each independently an aryl group having 6 to 25 carbon atoms, and R^(c) and R^(d) are each independently an alkyl group having 1 to 20 carbon atoms.

Unless particularly defined otherwise in this specification, the term “alkyl group” may, for example, refer to an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched or cyclic structure, and may be optionally substituted with one or more substituents. For example, the alkyl group that may be used herein may include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a cyclohexyl group, an octyl group, a nonyl group, or a decyl group.

Unless particularly defined otherwise in this specification, the term “alkoxy group” may, for example, refer to an alkoxy group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The alkoxy group may have a linear, branched or cyclic structure, and may be optionally substituted with one or more substituents. For example, the alkoxy group that may be used herein may include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, or a tert-butoxy group.

Unless particularly defined otherwise in this specification, the term “alkenyl group” may, for example, refer to an alkenyl group having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms. The alkenyl group may have a linear, branched or cyclic structure, and may be optionally substituted with one or more substituents. For example, the alkenyl group that may be used herein may include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, a cyclohexenyl group, an octenyl group, or a decenyl group.

Unless particularly defined otherwise in this specification, the term “epoxy group” may, for example, refer to a monovalent residue derived from a cyclic ether having three ring-forming atoms, or a compound including the cyclic ether. The epoxy group that may be used herein may include a glycidyl group, an epoxyalkyl group, a glycidoxyalkyl group, or an alicyclic epoxy group. As such, the alicyclic epoxy group may, for example, refer to a monovalent residue that has an aliphatic hydrocarbon ring structure and is derived from a compound having a structure in which two carbon atoms used to form the aliphatic hydrocarbon ring are also used to form an epoxy group. The alicyclic epoxy group may be an alicyclic epoxy group having 6 to 12 carbon atoms, for example, a 3,4-epoxycyclohexylethyl group.

Unless particularly defined otherwise in this specification, the term “aryl group” may also refer to a monovalent residue derived from a compound or a derivative thereof, which contains a benzene ring and has a structure in which two or more benzene rings are connected or condensed. In general, a category of the term “aryl group” may include an aralkyl group or an arylalkyl group in addition to the aryl groups normally referred to as aryl groups. For example, the aryl group may be an aryl group having 6 to 25 carbon atoms, 6 to 21 carbon atoms, 6 to 18 carbon atoms, or 6 to 12 carbon atoms. Examples of the aryl group may include a phenyl group, a dichlorophenyl group, a chlorophenyl group, a phenylethyl group, a phenylpropyl group, a benzyl group, a tolyl group, a xylyl group, or a naphthyl group.

In this specification, examples of the substituent which may be optionally substituted with the alkyl group, the alkenyl group, the alkoxy group, the epoxy group or the aryl group may include a halogen, an epoxy group, an acryloyl group, a methacryloyl group, an isocyanate group, a thiol group, a hydroxyl group, an alkyl group, an alkenyl group, an alkoxy group, an epoxy group, or an aryl group, but the present invention is not limited thereto.

The linear polysiloxane may include at least one alkenyl group bound to a silicon atom. According to one exemplary embodiment, the linear polysiloxane may include at least an alkenyl group bound to a silicon atom present in an end of the polysiloxane. For example, the linear polysiloxane may include at least an alkenyl group(s) bound to a silicon atom(s) of the unit M present in one or both ends of the polysiloxane. However, the alkenyl group may also be bound to a side chain of the linear polysiloxane, that is, a unit D forming the main chain.

According to one exemplary embodiment, the linear polysiloxane may be represented by the following Formula A.

In Formula A, R^(a) and R^(b) are each independently an aryl group having 6 to 25 carbon atoms, R^(c) and R^(d) are each independently an alkyl group having 1 to 20 carbon atoms, R^(e) is an alkenyl group having 2 to 20 carbon atoms, R^(f) is each independently an alkyl group having 1 to 20 carbon atoms, and m and n are positive numbers, provided that m/n ranges from 1 to 5.

In Formula A, m and n represent values of the unit D of Formula 1 and the unit D of Formula 2, respectively. For example, m may be in a range of approximately 5 to 100, approximately 5 to 90, approximately 5 to 80, approximately 5 to 70, approximately 5 to 60, approximately 5 to 50, approximately 5 to 40, approximately 5 to 30, or approximately 10 to 30, and n may be in a range of approximately 4 to 90, approximately 4 to 80, approximately 4 to 70, approximately 4 to 60, approximately 4 to 50, approximately 4 to 40, approximately 4 to 30, approximately 4 to 20, approximately 4 to 15, or approximately 5 to 15. When m and/or n in Formula A are present in plural numbers, the units D of Formulas 1 and 2 may be, for example, alternately disposed with regular periodicity as seen in a shape of a block copolymer, or irregularly disposed as seen in a shape of a random copolymer. In Formula A, m/n may be in a range of approximately 1 to 5, or approximately 1.5 to 3.

The mixture included in the curable composition may include a siloxane oligomeric compound. The oligomeric compound may serve to maintain a viscosity of the composition at a proper level. When the linear polysiloxane including the units D of Formulas 1 and 2 is used, the curable composition or the cured product thereof may have a high refractive index. However, the linear polysiloxane may have a structural characteristic to highly increase the viscosity of the composition. Therefore, when the composition is mixed with the oligomeric compound, viscosity and workability of the composition may be excellently maintained.

According to one exemplary embodiment, the siloxane oligomeric compound may be a compound represented by the following Formula 3:

In Formula 3, R₁ is an alkenyl group having 2 to 20 carbon atoms, R₂ is each independently an alkyl group having 1 to 20 carbon atoms, R₃ is an aryl group having 6 to 25 carbon atoms, R₄ is hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, an epoxy group, an alkenyl group having 2 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms, and k is a positive number.

In Formula 3, R₄ may be, for example, an aryl group having 6 to 25 carbon atoms.

In Formula 3, k is a positive number, for example, a positive number ranging from 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6, or 2 to 5. Within this range, a refractive index of the curable composition or the cured product thereof, and a viscosity of the composition may be maintained at a desired level.

For example, the mixture may include the oligomeric compound in an amount of 1 to 50 parts by weight or 5 to 50 parts by weight, relative to 100 parts by weight of the linear polysiloxane. Within this weight range, a viscosity, a refractive index, hardness and adhesive strength of the composition or the cured product thereof may be efficiently maintained.

Unless particularly defined otherwise in this specification, the term “part(s) by weight” means a weight ratio between respective components.

Both the linear polysiloxane and the oligomeric compound included in the mixture may include an alkenyl group bound to a silicon atom. According to one exemplary embodiment, a molar ratio (Ak/Si) of the total alkenyl groups (Ak) bound to silicon atoms present in the mixture with respect to the total silicon atoms (Si) present in the mixture may be, for example, in a range of 0.02 to 0.2, or 0.02 to 0.15. Within this molar ratio range, a curing property of the composition, and surface characteristics and hardness and crack resistance of the cured product may be excellently maintained.

According to one exemplary embodiment, the mixture including the linear polysiloxane and the siloxane oligomeric compound may have a viscosity at 25° C. of, for example, 500 cP to 100,000 cP, or 500 cP to 50,000 cP. Within this viscosity range, processability and hardness characteristics of the curable composition may be properly maintained.

The viscosities of the linear polysiloxane and the siloxane oligomeric compound included in the mixture are not particularly limited as long as the viscosity of the mixture is maintained within this viscosity range. For example, the linear polysiloxane may have a viscosity at 25° C. of approximately 10,000 cP to 10,000,000 cP, and the siloxane oligomeric compound may have a viscosity at 25° C. of approximately 50 cP to 5,000 cP.

According to one exemplary embodiment, the linear polysiloxane may have a weight average molecular weight (M_(w)) of, for example, approximately 500 to 50,000, or approximately 500 to 30,000. In this specification, the term “weight average molecular weight” refers to a value converted with respect to a polystyrene standard as measured by gel permeation chromatography (GPC). Unless particularly defined otherwise in this specification, the term “molecular weight” may also refer to a weight average molecular weight. Within this molecular weight range, viscosity, formability, hardness, crack resistance and strength characteristics of the composition or cured product thereof may be properly maintained.

For example, the oligomeric compound may also have a molecular weight of approximately 300 to 2,500, or approximately 500 to 1,500. Within this molecular weight range, a refractive index of the composition or cured product thereof may be maintained at a high level, and viscosity of the of the composition or cured product thereof may also be properly maintained.

The linear polysiloxane or the oligomeric compound may be prepared, for example, using a method of preparing a conventional siloxane compound as known in the related art. For example, the compounds may be prepared by properly hydrolyzing and condensing an organosilane compound containing a functional group, such as a halogen or an alkoxy group, which may take part in a hydrolytic and/or condensation reaction, or a partially hydrolyzed/condensed product thereof in consideration of a desired siloxane unit.

For example, the hydrolytic and condensation reaction may be performed in the presence of an acid catalyst or a base catalyst. Also, the organosilane compound that may be used herein may, for example, include a compound represented by the expression: Z_(n)SiX_((4-n)). As such, X may be a hydrolytic group, for example, a halogen such as chlorine, or an alkoxy group, and n may be an integer ranging from 2 to 3. As such, Z may also be a substituent bound to a silicon atom, which may be properly selected in consideration of a desired substituent of the polysiloxane or the oligomeric compound.

The linear polysiloxane or the siloxane oligomeric compound may be prepared, for example, by subjecting a cyclic siloxane compound to a ring-opening reaction. For example, the ring-opening reaction may be performed in the presence of a base catalyst.

As known in the related art, there are various methods, such as a re-equilibration reaction, which can be used to prepare a polysiloxane or a siloxane oligomer, and a person having ordinary skill in the art may properly select and employ the known methods in consideration of a target product.

The curable composition may include a silicon compound containing a hydrogen atom bound to a silicon atom. For example, the silicon compound may serve as a cross-linking agent that cross-links the linear polysiloxane and/or the oligomeric compound in a curing process.

A compound that may serve as a cross-linking agent as described above may be used as the silicon compound without particular limitation. For example, a compound known in the related art may be used as the silicon compound.

The silicon compound may include at least one hydrogen atom bound to a silicon atom. In this case, such a hydrogen atom may react with an alkenyl group of the linear polysiloxane or the siloxane oligomeric compound. For example, a molar ratio (H/Si) of hydrogen atoms (H) bound to silicon atoms with respect to the total silicon atoms (Si) included in the silicon compound may be in a range of 0.2 to 0.8, or 0.3 to 0.75. Within this molar ratio range, a curing property of the composition may be properly maintained, and crack resistance and thermal shock resistance of the cured product may also be properly maintained.

The silicon compound may include at least one aryl group bound to a silicon atom, for example, an aryl group having 6 to 25 carbon atoms. When the silicon compound includes an aryl group, a refractive index or hardness and moisture permeability of the cured product thereof may be more properly maintained. According to one exemplary embodiment, a molar ratio (Ar/Si) of the total aryl groups (Ar) included in the silicon compound with respect to the total silicon atoms (Si) included in the silicon compound may be, for example, in a range of 0.4 to 1.5, or 0.5 to 1.2. Within this molar ratio range, viscosity, a refractive index or hardness of the composition or cured product thereof may be excellently maintained.

Also, the silicon compound may have a viscosity at 25° C. of 1,000 cP or less, or 500 cP or less. Within this viscosity range, processability or hardness of the curable composition may be properly maintained.

In addition, the silicon compound may have a molecular weight of less than 1,000 or less than 800. Within this molecular weight range, hardness of the cured product may be properly maintained. Also, a lower limit of the molecular weight of the silicon compound is not particularly limited, and may be, for example, approximately 250.

According to one exemplary embodiment, a compound including a unit represented by the following Formula 4 may be, for example, used as the silicon compound.

H_(a)Y_(b)SiO_((4-a-b)/2)  [Formula 4]

In Formula 4, Y represents a monovalent hydrocarbon group having 1 to 25 carbon atoms, a is in a range of 0.3 to 1, and b is in a range of 0.9 to 2.

Unless particularly defined otherwise in this specification, for example, the term “monovalent hydrocarbon group” may refer to a monovalent residue derived from an organic compound composed of carbon and hydrogen atoms, or a derivative thereof. For example, the monovalent hydrocarbon group that may be used herein may include an alkyl group, an alkenyl group, an alkoxy group, or an aryl group. As such, specific kinds of the alkyl group, the alkenyl group, the alkoxy group or the aryl group are as listed above.

When Y in Formula 4 is present in plural numbers, Y may be the same as or different from each other.

For example, the silicon compound including the unit of Formula 4 may include compounds represented by the following Formulas B to G, but the present invention is not limited thereto.

(HMe₂SiO_(1/2))₂(MePhSiO_(2/2))₂  [Formula B]

(HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(1.5)  [Formula C]

(HMe₂SiO_(1/2))₂(MePhSiO_(2/2))_(1.5)(Ph₂SiO_(2/2))_(1.5)  [Formula D]

(HMe₂SiO_(1/2))₂(Me₂SiO_(2/2))_(2.5)(Ph₂SiO_(2/2))_(2.5)  [Formula E]

(HMe₂SiO_(1/2))₂(HMeSiO_(2/2))₁(Ph₂SiO_(2/2))₂  [Formula F]

(HMe₂SiO_(1/2))₃(PhSiO_(3/2))₁  [Formula G]

In Formulas B to Me represents a methyl group, and Ph represents a phenyl group.

The above-described silicon compound may be prepared, for example, using a method used to prepare the linear polysiloxane or the oligomeric compound.

For example, the silicon compound may be included in an amount of 10 to 500 parts by weight, or 50 to 400 parts by weight, relative to 100 parts by weight of the mixture of the linear polysiloxane and the oligomeric compound.

However, the content of the silicon compound is one exemplary embodiment, and may be, for example, specifically set based on an amount of the alkenyl groups present in the curable composition. For example, the silicon compound may be present in the curable composition so that a molar ratio (H/Ak) of hydrogen atoms (H) present in the silicon compound with respect to the total alkenyl groups present in the curable composition, for example, the total alkenyl groups (Ak) present in the linear polysiloxane, the oligomeric compound and a cross-linked polysiloxane to be described later, can be in a range of approximately 0.8 to 1.2. Within this molar ratio range, a curing property of the curable composition, and hardness and thermal shock resistance of the cured product thereof may be excellently maintained.

Also, the curable composition may further include a cross-linked polysiloxane as a certain component.

In this specification, the term “cross-linked polysiloxane” may refer to a polysiloxane including at least a unit T or a unit Q.

According to one exemplary embodiment, the cross-linked polysiloxane may include at least one siloxane unit selected from the group consisting of the units M, D, T and Q. In this case, the cross-linked polysiloxane may be a polysiloxane in which the unit T or Q is essentially present among the siloxane units included in the cross-linked polysiloxane.

The cross-linked polysiloxane may include at least one alkenyl group bound to a silicon atom. According to one exemplary embodiment, a molar ratio (Ak/Si) of alkenyl groups (Ak) included in the cross-linked polysiloxane with respect to the total silicon atoms (Si) included in the cross-linked polysiloxane may be, for example, in a range of 0.15 to 0.4, or 0.15 to 0.35. Within this molar ratio range, a curing property, crack resistance and thermal shock resistance of the curable composition or cured product thereof may be properly maintained.

In consideration of the refractive index or hardness, the cross-linked polysiloxane may also include at least one aryl group bound to a silicon atom. According to one exemplary embodiment, a molar ratio (Ar/Si) of the total aryl groups (Ar) included in the cross-linked polysiloxane with respect to the total silicon atoms (Si) included in the cross-linked polysiloxane may be, for example, in a range of 0.4 to 1.2, or 0.4 to 1.0. Within this molar ratio range, a refractive index, hardness and viscosity of the composition or cured product thereof may be properly maintained.

Also, the cross-linked polysiloxane may have a viscosity at 25° C. of 1,000 cP or more, or 2,000 cP or more. Within this viscosity range, processability of the curable composition and hardness of the cured product may be excellently maintained. An upper limit of the viscosity of the cross-linked polysiloxane is not particularly limited.

In addition, the cross-linked polysiloxane may have a molecular weight of 300 to 10,000, or 500 to 5,000. Within this molecular weight range, formability, hardness and viscosity of the composition or cured product thereof may be properly maintained.

According to one exemplary embodiment, the cross-linked polysiloxane may be represented by an average composition equation of the following Formula 5.

(R⁵R⁶R⁷SiO_(1/2))_(c)(R⁸R⁹SiO_(2/2))_(d)(R¹⁰SiO_(3/2))_(e)(SiO_(4/2))_(f)  [Formula 5]

In Formula 5, R⁵ to R¹⁰ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, an epoxy group, an alkenyl group having 2 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms, provided that, when each of R⁵ to R¹⁰ is present in plural numbers, each of R⁵ to R¹⁰ may be the same as or different from each other, and at least one of R⁵ to R¹⁰ is an alkenyl group having 2 to 20 carbon atoms, and provided that, when c+d+e+f is set to 1, c is in a range of 0 to 0.5, d is in a range of 0 to 0.3, e is in a range of 0 to 0.8, and f is in a range of 0 to 0.2, provided that e and f are not 0 at the same time.

In this specification, a polysiloxane represented by a predetermined average composition equation includes a case in which a polysiloxane is composed of a single component represented by the predetermined average composition equation, as well as cases in which the polysiloxane is composed of a mixture of at least two components, and an average composition of the two components in the mixture is represented by the predetermined average composition equation.

In the cross-linked polysiloxane, the units M, D, T and Q may be properly allocated in consideration of a purpose. In the average composition equation of Formula 5, (e+(4/3)f)/(c+2d) may be, for example, in a range of approximately 2 to 5, or approximately 2 to 4. Also, e/(e+f) in the average composition equation of Formula 5 may be equal to or greater than approximately 0.85 or approximately 0.9. When the units M, D, T and Q are allocated as described above, hardness, crack resistance and thermal shock resistance of the curable composition or cured product thereof may be excellently maintained. Meanwhile, an upper limit of e/(e+f) in Formula 5 may be 1.

Examples of the above-described cross-linked polysiloxane may include compounds represented by the following Formulas H to M, but the present invention is not limited thereto.

(ViMe₂SiO_(1/2))₃(PhSiO_(3/2))₁₀  [Formula H]

(ViMe₂SiO_(1/2))₂(MePhSiO_(2/2))₂(PhSiO_(3/2))₁₅  [Formula I]

(ViMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))₁(PhSiO_(3/2))₈  [Formula J]

(ViMe₂SiO_(1/2))₃(PhSiO_(3/2))₉(SiO_(4/2))₁  [Formula K]

(ViMe₂SiO_(1/2))₃(MePhSiO_(2/2))₁(PhSiO_(3/2))₉(SiO_(4/2))₁  [Formula L]

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₁(MePhSiO_(2/2))₂(Ph₂SiO_(2/2))₁(PhSiO_(3/2))₁₉(SiO_(4/2))₁  [Formula M]

In Formulas H to M, Vi, Me and Ph represent a vinyl group, a methyl group and a phenyl group, respectively.

For example, the cross-linked polysiloxane may be prepared in the same manner as in the linear polysiloxane.

The cross-linked polysiloxane may be, for example, included in an amount of 50 to 700 parts by weight, or 50 to 500 parts by weight, relative to 100 parts by weight of the mixture of the linear polysiloxane and the siloxane oligomeric compound. Within this content range, hardness, crack resistance and thermal shock resistance of the curable composition or cured product thereof may be properly maintained.

In the curable composition, the silicon compound or cross-linked polysiloxane containing a hydrogen atom may include at least one aryl group bound to a silicon atom, as described above. According to one exemplary embodiment, a molar ratio (Ar/Si) of the total aryl groups (Ar) bound to silicon atoms included in the curable composition with respect to the total silicon atoms (Si) included in the curable composition may be, for example, in a range of 0.4 to 1.5, or 0.7 to 1.2. Within this molar ratio range, hardness, viscosity and a refractive index of the curable composition or cured product thereof may be properly maintained.

In the curable composition including the cross-linked polysiloxane according to one exemplary embodiment, both the silicon compound and cross-linked polysiloxane may include at least one aryl group bound to a silicon atom.

In this case, the curable composition may satisfy the requirements of the following General Formula 1 and/or 2:

|X _((A)) −X _((C))|≦0.4  [General Formula 1]

|X _((C)) −X _((B))|≦0.4[General Formula 2]

In General Formulas 1 and 2, X_((A)) is a molar ratio (Ar/Si) of the total aryl groups (Ar) included in the mixture of the linear polysiloxane and the siloxane oligomer with respect to the total silicon atoms (Si) included in the mixture, X_((B)) is a molar ratio (Ar/Si) of the total aryl groups (Ar) included in the silicon compound with respect to the total silicon atoms (Si) included in the silicon compound, and X_((C)) is a molar ratio (Ar/Si) of the total aryl groups (Ar) included in the cross-linked polysiloxane with respect to the total silicon atoms (Si) included in the cross-linked polysiloxane.

When the absolute value of a difference between X_((A)) and X_((C)) and/or the absolute value of a difference between X_((C)) and X_((B)) is set to 0.4 or less as described above, compatibility between components of the curable composition may be properly maintained, and transparency of the curable composition or cured product thereof may also be properly maintained. According to another exemplary embodiment, the absolute value of the difference between X_((A)) and X_((C)) and/or the absolute value of the difference between X_((C)) and X_((B)) may be less than 0.4.

In addition, the curable composition may further include a hydrosilylation reaction catalyst. In this case, the hydrosilylation reaction catalyst may be added to facilitate curing and cross-linking reactions of the components of the curable composition.

A conventional hydrosilylation reaction catalyst known in the related art may be used as the hydrosilylation reaction catalyst without particular limitation.

For example, the hydrosilylation reaction catalyst that may be used herein may include at least one selected from the group consisting of a platinum-based catalyst, a palladium-based catalyst and a rhodium-based catalyst. For example, a platinum-based catalyst may be used in the curable composition. In general, chloroplatinic acid, platinum tetrachloride, an olefin complex of platinum, an alkenyl siloxane complex of platinum, and/or a carbonyl complex of platinum may be used as the platinum-based catalyst.

For example, the curable composition may include the hydrosilylation reaction catalyst at an effective amount to serve as a catalyst. For example, the hydrosilylation reaction catalyst may be used so that an atomic weight may be in a range of approximately 0.1 ppm to 500 ppm, or approximately 0.2 ppm to 100 ppm, based on the mass of platinum, palladium or rhodium in the curable composition.

Also, the curable composition may further include a tackifier to improve an adhesive property to various bases. A component that can improve a self-adhesive property of the curable composition or cured product thereof, particularly a component that can improve a self-adhesive property for a metal and an organic resin, may be used as the tackifier.

The tackifier that may be used herein may include a silane compound containing one or two or more functional groups selected from the group consisting of an alkenyl group (i.e., a vinyl group), a (meth)acryloyloxy group, a hydrosilyl (SiH) group, an epoxy group, an alkoxy group, a carbonyl group and a phenyl group; or an organic silicon compound such as a cyclic or linear siloxane compound having 2 to 30 silicon atoms or 4 to 20 silicon atoms, but the present invention is not limited thereto.

When the tackifier is included in the composition, the tackifier may be, for example, included in an amount of approximately 0.1 to 10 parts by weight, relative to 100 parts by weight of the linear polysiloxane compound or 100 parts by weight of the mixture of the linear polysiloxane and the oligomeric compound. However, the content of the tackifier may be properly altered in consideration of an effect of improving a desired adhesive property.

For example, the curable composition may further include particles such as inorganic particles. For example, particles having a refractive index such that an absolute value of a difference in refractive index between the particles and the composition or cured product thereof can be equal to or less than 0.1, may be used as the particles.

For example, when the particles are blended with a fluorescent material in the curable composition, precipitation of the fluorescent material caused during a curing process may be prevented, and heat resistance, a heat-dissipating property and crack resistance may also be improved, thereby improving reliability as a whole. Since the particles have the refractive index, the particles may also serve to maintain transparency of the curable composition or cured product thereof while showing the above-described functions. Therefore, when the particles are applied to a device, brightness of the curable composition or cured product thereof may be improved.

Various kinds of particles used in the related art may be used as the particles as long as an absolute value of a difference in refractive index between the composition excluding the above-described particles or a cured product thereof and the particles is equal to or less than 0.1. Here, the absolute value of the difference in refractive index between the composition excluding the above-described particles or the cured product thereof and the particles may be preferably equal to or less than 0.07, more preferably 0.05. For example, the particles that may be used herein may include silica (SiO₂), organosilica, alumina, aluminosilica, titania, zirconia, cerium oxide, hafnium oxide, niobium oxide, tantalum pentoxide, indium oxide, tin oxide, indium tin oxide, zinc oxide, silicon, zinc sulfide, calcium carbonate, barium sulfate, aluminosilicate, or magnesium oxide. In this case, the particles may be in a porous shape or a hollow particle shape.

An average particle size of the particles may be, for example, in a range of 1 nm to 50 m, preferably 2 nm to 10 m. When the particles have an average particle size of 1 nm or more, the particles may be uniformly dispersed in the curable composition or cured product thereof. On the other hand, when the particles have an average particle size of 50 m or less, dispersion of the particles may be effectively performed, and precipitation of the particles may also be prevented.

The particles may be included in the curable composition in an amount of 0.1 to 30 parts by weight, or 0.2 to 10 parts by weight, relative to 100 parts by weight of the linear polysiloxane, the mixture of the linear polysiloxane and the oligomeric compound, or the sum of the cross-linked polysiloxane and the mixture of the linear polysiloxane and the oligomeric compound. When the content of the particles exceeds 0.1 parts by weight, precipitation of the fluorescent material may be effectively inhibited, or reliability of a device may be improved, whereas processability may be excellently maintained when the content of the particles is less than 30 parts by weight.

In addition to the above-described components, the curable composition may also include a reaction inhibitor such as 2-methyl-3-butyn-2-ol, 2-phenyl-3-1-butyn-2-ol, 3-methyl-3-penten-1-yne, 3,5,-dimethyl-3-hexen-1-yne or 1,3,5,7-tetramethyl,1,3,5,7-tetrahexenylcyclotetrasiloxane, as necessary. Also, the curable composition may further include a carbon-functional silane and a partially hydrolyzed/condensed product thereof, which contains an epoxy group and/or an alkoxysilyl group, or a tackifier such as a siloxane compound as any other component without causing damage to a desired purpose.

According to one exemplary embodiment, the curable composition may also further include a fluorescent material. Kinds of fluorescent materials that may be used herein are not particularly limited. For example, a kind of a conventional fluorescent material applied to an LED package may be used to realize white light.

Another aspect of the present invention provides a semiconductor device. The semiconductor device according to one exemplary embodiment may be encapsulated by an encapsulation material including a cured product of the curable composition.

As such, examples of the semiconductor device encapsulated by the encapsulation material may include a diode, a transistor, a thyristor, a photo coupler, a charge coupled device (CCD), a solid-phase image pickup device, an integral integrated circuit (IC), a hybrid IC, a large-scale integration (LSI), a very-large-scale integration (VLSI), and an LED.

According to one exemplary embodiment, the semiconductor device may be a light emitting diode.

For example, the light emitting diode that may be used herein may include a light emitting diode formed by stacking a semiconductor material on a substrate. Examples of the semiconductor material may include GaAs, GaP, GaAlAs, GaAsP, AlGaInP, GaN, InN, AlN, InGaAlN or SiC, but the present invention is not limited thereto. Also, examples of the substrate may include a monocrystalline material such as sapphire, spinel, SiC, Si, ZnO or GaN.

In manufacture of an LED, a buffer layer may also be formed between the substrate and the semiconductor material, as necessary. GaN or MN may be used for the buffer layer. A method of stacking a semiconductor material on a substrate is not particularly limited. For example, the semiconductor material may be stacked using a method such as metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HDVPE), or congruent melt growth. Also, a structure of the LED may be, for example, a monojunction, a heterojunction, or a dual heterojunction junction such as an MIS junction, a PN junction, or a PIN junction. Also, the LED may be formed with a single or multiple quantum well structure.

According to one exemplary embodiment, an emission wavelength of the LED may be, for example, in a range of 250 nm to 550 nm, preferably 300 nm to 500 nm, and more preferably 330 nm to 470 nm. The emission wavelength may refer to a major emission peak wavelength. When the emission wavelength of the LED is set to this wavelength range, a white LED having high energy efficiency and excellent color reproducibility may be obtained with a longer lifespan.

The LED may be encapsulated using the curable composition. Also, the LED may be encapsulated only by the curable composition, or another encapsulation material may be optionally used together with the curable composition. When two kinds of encapsulation materials are used together, encapsulation of an LED may be performed by encapsulating the LED with the curable composition and encapsulating the curable composition with another encapsulation material, or by encapsulating the LED with another encapsulation material and encapsulating the encapsulation material with the curable composition. Another encapsulation material may include an epoxy resin, a silicone resin, an acrylic resin, a urea resin, an imide resin, or glass.

As a method of encapsulating an LED with the curable composition, for example, a method of injecting a curing composition into a mold-type cast in advance, dipping a lead frame in which an LED is fixed in the curable composition and curing the curable composition, or a method of injecting a curing composition into a cast having an LED inserted therein and curing the curing composition, may be used. A method of injecting a composition may include injection using a dispenser, transfer molding, or injection molding. As another encapsulation method, a method of coating a composition on an LED using a method such as dripping, stencil printing, or screen printing, or a mask and curing the composition, or a method of injecting a composition into a cup having an LED disposed at a lower portion thereof using a dispenser and curing the composition may also be used.

Also, the composition may be used as a die-bond material for fixing an LED in a lead terminal or a package, or used for a passivation film or a package substrate formed on an LED, as necessary.

When curing of the composition is required, the curing method is not particularly limited. For example, the composition may be cured at a constant temperature of 60° C. to 200° C. for 10 minutes to 5 hours, or a series of curing processes may be carried out by performing two or more operations at a suitable temperature for a suitable period of time.

The shape of the encapsulation material is not particularly limited. For example, the encapsulation material may be formed in the form of a shell-shaped lens, a plate, or a thin film.

Also, performance of the LED may be further improved using a method known in the prior art. For example, a method of improving performance may include a method of installing a light-reflecting layer or a light-condensing layer in a rear surface of an LED, a method of forming a complementary color-tinting unit at a bottom surface of an LED, a method of installing a layer for absorbing light having a shorter wavelength than a major emission peak on an LED, a method of encapsulating an LED and further molding the LED with a hard material, a method of fixing an LED in a through hole, or a method of bringing an LED into contact with a lead member using a method such as flip-chip bonding and extracting light in a direction of a substrate.

For example, the LED may be effectively applied to backlights for LCDs, lightings, light sources for various sensors, printers or photocopiers, light sources for dashboards in vehicles, traffic lights, pilot lamps, light sources for display devices or planar light emitting bodies, displays, decorations, or various lights.

Advantageous Effects

The curable composition according to one exemplary embodiment may show excellent processability and workability. Also, the curable composition may have a high refractive index before or after curing. The composition has low moisture permeability before or after curing and shows excellent crack resistance, thermal shock resistance, adhesive property and hardness. In addition, the composition does not cause color change, such as whitening, under a high-temperature or high-humidity condition, and does not exhibit stickiness on a surface thereof. According to one exemplary embodiment, the curable composition may be used as an adhesive material or as an encapsulation material for semiconductor devices such as an LED, a CCD, a photo coupler, or a photovoltaic cell.

BEST MODE

Hereinafter, the curable composition will be described in detail with reference to Examples and Comparative Examples. However, it should be understood that the following Examples are not intended to limit the scope of the curable composition.

Hereinafter, the symbols Vi, Ph, Me and Ep represent a vinyl group, a phenyl group, a methyl group and a glycidoxypropyl group, respectively.

Also, the physical properties are measured as follows:

1. Evaluation of Hardness

Each of the curable compositions prepared in Examples and Comparative Examples was injected into a square specimen mold, and cured at 150° C. for 1 hour to prepare a specimen. Then, the specimen was measured for hardness using a Shore-D durometer (specimen thickness: 4 mm).

2. Measurement of Refractive Index

The curable compositions prepared in Examples and Comparative Examples were dispensed in an aluminum dish, and cured at 150° C. for 1 hour. Thereafter, the curable compositions were measured for refractive index using an Abbe refractometer. nD of a test piece used was 1.7393.

3. Measurement of Light Transmittance

Each of the curable compositions prepared in Examples and Comparative Examples was injected between two glass plates with a 1 mm-thick spacer interposed therebetween, and cured at 150° C. for 1 hour. Then, the curable compositions were measured for light transmittance in a thickness direction of a specimen with respect to light with a wavelength of 450 nm using a UV-vis spectrometer.

4. Measurement of Moisture Permeability

Each of the curable compositions prepared in Examples and Comparative Examples was injected between two glass plates with a 1 mm-thick spacer interposed therebetween, cured at 150° C. for 1 hour, and then cut into pieces having a suitable size to be installed in a water vapor permeation analyzer, thereby preparing specimens. The moisture permeability of the specimens having an area of 10 cm² was continuously measured at a temperature of 37.8° C. and a relative humidity of 100% for at least one day using a moisture permeability measurement apparatus, Mocon WVTR permatron-W. Then, a value (unit: g/m²/day) at a point of time at which the moisture permeability stabilized was calculated.

5. Measurement of Formability

The formability was evaluated according to the following criteria by determining whether respective components are mixed in preparation of a curable composition, and a mixture of the components is moldable according to the flowability of a composition.

<Evaluation Criteria for Formability>

◯: Respective components are miscible and a mixture of the components is moldable

x: Respective components are not miscible and/or a mixture of the components is not moldable

6. Evaluation of Device Properties

The device properties were evaluated using an LED package prepared with polyphthalamide (PPA). More particularly, a curable composition was dispensed into a PPA cup, and cured at a constant temperature of 60° C. for 30 minutes, and then at a constant temperature of 150° C. for 1 hour to manufacture a surface-mounted LED. Then, a thermal shock test and an IR Reflow test were carried out, as follows:

(1) Thermal Shock Test

One cycle, in which the prepared surface-mounted LED was kept at a constant temperature of −50° C. for 30 minutes, and then kept at a constant temperature of 100° C. for 30 minutes, was repeated 10 times (i.e., a total of 10 cycles). Then, the surface-mounted LED was cooled at room temperature, and a peeling state in the interface between the PPA and the cured product of the curable composition was evaluated under an optical microscope to determine the thermal shock resistance. During the evaluation, a total of 10 surface-mounted LEDs prepared with the same curable composition were subjected to the thermal shock test, and the number of peeled LEDs was counted.

(2) IR Reflow Test

The prepared surface-mounted LED was passed three times through an IR reflow trail at a set temperature of 160° C. for 2 minutes and a set temperature of 270° C. for 2 minutes. Then, a peeling state in the interface between the PPA and the cured product of the curable composition was evaluated under an optical microscope. During the evaluation, a total of 10 surface-mounted LEDs prepared with the same curable composition were subjected to the IR reflow test, and the number of peeled LEDs was counted.

Synthesis Example 1 Preparation of Oligomeric Compound (A)

11 g of hexaphenylcyclotrisiloxane was dissolved in 80 ml of tetrahydrofuran (THF), and a solution obtained by mixing 8 g of water with 0.6 g of n-hexylamine was then added to the resulting mixture to prepare a reaction solution. The reaction solution was stirred at room temperature for 30 minutes, and thin layer chromatography (TLC) was performed to determine whether the hexaphenylcyclotrisiloxane was completely removed. Subsequently, the reaction solution was mixed with 100 ml of water, and diluted with a solution of dilute hydrochloric acid to a proper level. Thereafter, a reaction product was extracted from 120 ml of toluene, and recrystallized to obtain a white solid. 9.58 g of the prepared compound in a white solid form was dissolved in toluene, and a mixture including 4.79 g of dimethylvinylchlorosilane and 4.79 g of tetraethylammonium (TEA) was mixed with the solution. Then, the resulting mixture was reacted at 40° C. for 1 hour, and the reaction solution was mixed with 72 ml of water. Subsequently, an organic layer was separated and washed with water, and water was then removed on MgSO₄. Thereafter, a solvent was removed using a rotary evaporator to prepare an oligomeric compound (A) represented by Formula 3 in which R₁ represents a vinyl group, R₂ represents a methyl group, R₃ and R₄ are each independently a phenyl group, and k is 3. The oligomeric compound (A) was obtained in the form of a white solid having a refractive index of approximately 1.561 and a molecular weight of approximately 564.

Synthesis Example 2 Preparation of Oligomeric Compound (B)

40 g of octaphenylcyclotetrasiloxane and 18.8 g of divinyltetramethyldisiloxane were put into a flask. Then, a catalyst, tetramethylammonium hydroxide (TMAH), and 0.05 g of KOH were added to the flask, and reacted for 4 hours. Subsequently, the TMAH catalyst was inactivated at 140° C. for 30 minutes, and 100 ml of ether was added to the resulting reaction solution. The ether-added solution was washed with an ammonium chloride (NH₄Cl) solution and water, and a solvent was removed using a rotary evaporator to prepare an oligomeric compound (B) represented by Formula 3 in which R₁ represents a vinyl group, R₂ represents a methyl group, R₃ and R₄ are each independently a phenyl group, and k is 4. The oligomeric compound (B) was obtained in the form of a clear oil having a refractive index of approximately 1.551, a molecular weight of approximately 598 and a viscosity at 25° C. of 267 cP.

Synthesis Example 3 Preparation of Oligomeric Compound (C)

An oligomeric compound (C) represented by Formula 3 in which R₁ represents a vinyl group, R₂ represents a methyl group, R₃ and R₄ are each independently a phenyl group, and k is 4.5, was prepared in the same manner as in Synthesis Example 2, except that the divinyltetramethyldisiloxane was used in an amount of approximately 9.4 g. The oligomeric compound (C) was obtained in the form of a clear oil having a refractive index of approximately 1.568, a molecular weight of approximately 685 and a viscosity at 25° C. of 2,950 cP.

Synthesis Example 4 Preparation of Linear Polysiloxane (A)

8.4 g of octamethylcyclotetrasiloxane, 44.92 g of octaphenylcyclotetrasiloxane, and 4.75 g of divinyltetramethyldisiloxane were uniformly mixed, and 0.04 g of KOH was added to the resulting mixture. Then, the mixture was reacted at 110° C. for 4 hours, and a low molecular weight material was then removed to prepare a linear polysiloxane (A). The linear polysiloxane (A) was a compound including the unit (Ph₂SiO_(2/2)) represented by Formula 1 and the unit (Me₂SiO_(2/2)) represented by Formula 2, wherein the unit (Ph₂SiO_(2/2)) was present at a ratio approximately 1.8 times higher than the unit (Me₂SiO_(2/2)), and both ends of a molecular chain thereof were also blocked with dimethylvinylsiloxy. The linear polysiloxane (A) was obtained in the form of a clear oil having a refractive index of approximately 1.570, a molecular weight of approximately 3,092 and a viscosity at 25° C. of 420,000 cP.

Synthesis Example 5 Preparation of Linear Polysiloxane (B)

A linear polysiloxane (B) was prepared in the same manner as in Synthesis Example 4, except that the octamethylcyclotetrasiloxane and the octaphenylcyclotetrasiloxane were used at contents of 6.3 g and 50.54 g, respectively. The linear polysiloxane (B) was a compound including the unit (Ph₂SiO_(2/2)) represented by Formula 1 and the unit (Me₂SiO_(2/2)) represented by Formula 2, wherein the unit (Ph₂SiO_(2/2)) was present at a ratio approximately 2.625 times higher than the unit (Me₂SiO_(2/2)), and both ends of a molecular chain thereof were also blocked with dimethylvinylsiloxy. The linear polysiloxane (B) was obtained in the form of a clear gum having a refractive index of approximately 1.580, a molecular weight of approximately 3,157 and a viscosity at 25° C. of greater than 5,000,000 cP.

Synthesis Example 6 Preparation of Linear Polysiloxane (C)

10.0 g of octamethylcyclotetrasiloxane, 91.9 g of tetraphenyltetramethylcyclotetrasiloxane, and 7.5 g of divinyltetramethyldisiloxane were uniformly mixed, and 0.04 g of KOH was added to the resulting mixture. Then, the mixture was reacted at 110° C. for 4 hours, and a low molecular weight material was then removed to prepare a linear polysiloxane (C). The linear polysiloxane (C) was a compound including the unit (PhMeSiO_(2/2)) instead of the unit of Formula 1 and the unit (Me₂SiO_(2/2)) of Formula 2, wherein the unit (PhMeSiO_(2/2)) was present at a ratio approximately 5 times higher than the unit (Me₂SiO_(2/2)), and both ends of a molecular chain thereof were also blocked with dimethylvinylsiloxy. The linear polysiloxane (C) had a refractive index of approximately 1.520 and a viscosity (at 25° C.) of approximately 6,200 cP.

Synthesis Example 7 Preparation of Linear Polysiloxane (D)

A linear polysiloxane (D) was prepared in the same manner as in Synthesis Example 5, except that the octamethylcyclotetrasiloxane, the octaphenylcyclotetrasiloxane and the divinyltetramethyldisiloxane were used at contents of 35.0 g, 40.1 g and 0.8 g, respectively. The linear polysiloxane (D) was a compound including the unit (Ph₂SiO_(2/2)) represented by Formula 1 and the unit (Me₂SiO_(2/2)) represented by Formula 2, wherein the unit (Ph₂SiO_(2/2)) was present at a ratio approximately 0.4 times higher than the unit (Me₂SiO_(2/2)), and both ends of a molecular chain thereof were also blocked with dimethylvinylsiloxy. The linear polysiloxane (D) was obtained in the form of a clear oil having a refractive index of approximately 1.472, a molecular weight of approximately 17,200 and a viscosity at 25° C. of greater than 13,900 cP.

Synthesis Example 8 Preparation of Linear Polysiloxane (E)

A linear polysiloxane (E) was prepared in the same manner as in Synthesis Example 5, except that the octamethylcyclotetrasiloxane and the octaphenylcyclotetrasiloxane were used at contents of 5.0 g and 93.6 g, respectively. The linear polysiloxane (E) was a compound including the unit (Ph₂SiO_(2/2)) represented by Formula 1 and the unit (Me₂SiO_(2/2)) represented by Formula 2, wherein the unit (Ph₂SiO_(2/2)) was present at a ratio approximately 7 times higher than the unit (Me₂SiO_(2/2)), and both ends of a molecular chain thereof were also blocked with dimethylvinylsiloxy. The linear polysiloxane (E) had a molecular weight of approximately 4,560 and was obtained in the form of a gum that was hard at 25° C.

Synthesis Example 9 Preparation of Linear Polysiloxane (F)

A linear polysiloxane (F) was prepared in the same manner as in Synthesis Example 5, except that the octamethylcyclotetrasiloxane and the octaphenylcyclotetrasiloxane were used at contents of 5.0 g and 60.2 g, respectively. The linear polysiloxane (F) was a compound including the unit (Ph₂SiO_(2/2)) represented by Formula 1 and the unit (Me₂SiO_(2/2)) represented by Formula 2, wherein the unit (Ph₂SiO_(2/2)) was present at a ratio approximately 4.5 times higher than the unit (Me₂SiO_(2/2)), and both ends of a molecular chain thereof were also blocked with dimethylvinylsiloxy. The linear polysiloxane (F) was obtained in the form of a gum having a refractive index of approximately 1.595, a molecular weight of approximately 2,500 and showing no flowability at 25° C.

Example 1

30 g of a polysiloxane, which was used as a cross-linked polysiloxane and represented by the expression (ViMe₂SiO_(1/2))₁(PhSiO_(3/2))₄ and had a molecular weight of approximately 1,500, and 11 g of a silicon compound (molecular weight: approximately 750), which was used as a silicon compound and had a dendritic structure including a unit represented by the expression H_(0.7)Me_(1.3)Ph_(0.7)SiO_(0.7), were added to a mixture obtained by mixing 1 g of the oligomeric compound (A) prepared in Synthesis Example 1 and 9 g of the polysiloxane (A) prepared in Synthesis Example 4. Then, a platinum-based catalyst (platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane) was added so thin an amount of Pt(0) amounted to 6 ppm to prepare a curable composition (A).

Example 2

A curable composition was prepared in the same manner as in Example 1, except that a mixture obtained by mixing 3 g of the oligomeric compound (B) prepared in Synthesis Example 2 and 7 g of the linear polysiloxane (B) prepared in Synthesis Example 5 was used instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Example 3

A curable composition was prepared in the same manner as in Example 1, except that a mixture obtained by mixing 2 g of the oligomeric compound (C) prepared in Synthesis Example 3 and 8 g of the linear polysiloxane (A) prepared in Synthesis Example 4 was used instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Example 4

A curable composition was prepared in the same manner as in Example 1, except that a mixture obtained by mixing 5 g of the oligomeric compound (A) prepared in Synthesis Example 1 and 9 g of the polysiloxane (F) prepared in Synthesis Example 9 was used instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Comparative Example 1

A curable composition was prepared in the same manner as in Example 1, except that 10 g of a polysiloxane (refractive index (h): 38, molecular weight: approximately 5,108, and viscosity (25° C.): approximately 5,630 cP) represented by the following Formula M was used instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Comparative Example 2

A curable composition was prepared in the same manner as in Example 1, except that 10 g of the polysiloxane (A) prepared in Synthesis Example 4 was used alone instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Comparative Example 3

A curable composition was prepared in the same manner as in Example 1, except that 10 g of the polysiloxane (B) prepared in Synthesis Example 5 was used alone instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Comparative Example 4

A curable composition was prepared in the same manner as in Example 1, except that 2 g of the oligomeric compound (A) prepared in Synthesis Example 1 and 8 g of the linear polysiloxane (C) prepared in Synthesis Example 6 were used instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Comparative Example 5

A curable composition was prepared in the same manner as in Example 1, except that 2 g of the oligomeric compound (A) prepared in Synthesis Example 1 and 8 g of the polysiloxane (D) prepared in Synthesis Example 7 were used instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

Comparative Example 6

A curable composition was prepared in the same manner as in Example 1, except that 5 g of the oligomeric compound (A) prepared in Synthesis Example 1 and 5 g of the polysiloxane (D) prepared in Synthesis Example 8 were used instead of the mixture including 1 g of the oligomeric compound (A) of Synthesis Example 1 and 9 g of the polysiloxane (A) of Synthesis Example 4.

The formability, hardness, refractive index, light transmittance (%) and moisture permeability measured for each of the curable compositions are summarized and listed in the following Tables 1 and 2.

TABLE 1 Examples 1 2 3 4 Formability ◯ ◯ ◯ ◯ Hardness 30 28 32 59 Refractive index 1.566 1.553 1.571 1.568 Light transmittance (%) 99.1 99.1 99.0 99.0 Moisture permeability (g/m²/day) 8.92 9.79 8.58 9.43 F: Not measured

TABLE 2 Comparative Examples 1 2 3 4 5 6 Formability ◯ X X ◯ ◯ X Hardness 20 F F 16 14 F Refractive index 1.540 F F 1.526 1.483 F Light transmittance (%) 99.2 F F 99.0 99.1 F Moisture permeability 11.89 F F 12.34 13.08 F (g/m²/day) F: Not measured

As seen from Tables 1 and 2, it was confirmed that the curable compositions prepared in the Examples had a high refractive index, hardness and light transmittance, and also showed low moisture permeability and excellent formability.

Meanwhile, it was revealed that not even a specimen was manufactured due to the very poor formability, and thus physical properties of the curable compositions were not measured in the case of Comparative Examples 2 and 3 in which the linear polysiloxane was used alone without mixing the oligomeric compound, or Comparative Example 6 in which the unit of Formula 1 was present at an excessively high ratio.

Also, it was revealed that the curable composition of Comparative Example 1 showed very poor hardness and moisture permeability characteristics.

In addition, it was confirmed that hardness or moisture barrier characteristics were very poor in the case of Comparative Examples 4 and 5 in which the polysiloxane which did not include the unit of Formula 1, was used, or in which the polysiloxane including the unit of Formula 1 at an excessively low ratio was used.

The device properties measured for each of the curable compositions are summarized and listed in the following Tables 3 and 4.

TABLE 3 Examples 1 2 3 4 IR reflow test (Number of Peeled 0/10 0/10 0/10 0/10 LEDs/Total number of LEDs) Thermal shock test (Number of 0/10 0/10 0/10 0/10 Peeled LEDs/Total number of LEDs) F: Not measured

TABLE 4 Comparative Examples 1 2 3 4 5 6 IR reflow test (Number of Peeled 2/10 F F 6/10 8/10 F LEDs/Total number of LEDs) Thermal shock test (Number of 3/10 F F 4/10 5/10 F Peeled LEDs/Total number of LEDs) F: Not measured

As seen from Tables 3 and 4, it was revealed that the peels were not observed in a total of 10 LED specimens used in the tests when the curable compositions prepared in the Examples were used. Meanwhile, it was revealed that the peels were observed in two out of the 10 total LED specimens used in the IR reflow test, and observed in three out of the 10 total LED specimens used in the thermal shock test when the curable composition prepared in Comparative Example 1 was used. In the case of Comparative Examples 2, 3 and 6, not even a specimen was manufactured due to the poor formability.

Also, a number of the peels were observed in the LED specimens in the case of Comparative Examples 4 and 5. 

1. A curable composition comprising: a mixture of a linear polysiloxane and an siloxane oligomeric compound represented by the following Formula 3, the linear polysiloxane comprising an alkenyl group bound to a silicon atom and comprising siloxane units represented by the following Formulas 1 and 2, in which a mole number of the siloxane unit of Formula 1 is 1 to 5 times higher than that of the siloxane unit of Formula 2; and a silicon compound comprising a hydrogen atom bound to a silicon atom:

wherein R^(a) and R^(b) are each independently an aryl group having 6 to 25 carbon atoms, R^(c) and R^(d) are each independently an alkyl group having 1 to 20 carbon atoms, R₁ is an alkenyl group having 2 to 20 carbon atoms, R₂ is each independently an alkyl group having 1 to 20 carbon atoms, R₃ is an aryl group having 6 to 25 carbon atoms, R₄ is hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, an epoxy group, an alkenyl group having 2 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms, and k is a positive number.
 2. The curable composition of claim 1, wherein the linear polysiloxane comprises an alkenyl group bound to a silicon atom at an end of the polysiloxane.
 3. The curable composition of claim 1, wherein the linear polysiloxane is represented by the following Formula A:

wherein R^(a) and R^(b) are each independently an aryl group having 6 to 25 carbon atoms, R^(c) and R^(d) are each independently an alkyl group having 1 to 20 carbon atoms, R^(e) is an alkenyl group having 2 to 20 carbon atoms, R^(f) is each independently an alkyl group having 1 to 20 carbon atoms, and m and n are positive numbers, provided that m/n ranges from 1 to
 5. 4. The curable composition of claim 1, wherein the “R₄” in Formula 3 represents an aryl group having 6 to 25 carbon atoms.
 5. The curable composition of claim 1, wherein the “k” in Formula 3 is in a range of 1 to
 10. 6. The curable composition of claim 1, wherein the mixture comprises the siloxane oligomeric compound in an amount of 1 to 50 parts by weight, relative to 100 parts by weight of the linear polysiloxane.
 7. The curable composition of claim 1, wherein the mixture has a viscosity at 25° C. of 500 cP to 100,000 cP.
 8. The curable composition of claim 1, wherein the linear polysiloxane has a weight average molecular weight of 500 to 50,000.
 9. The curable composition of claim 1, wherein the siloxane oligomeric compound has a weight average molecular weight of 300 to 2,500.
 10. The curable composition of claim 1, wherein the silicon compound comprises at least one aryl group that comprises 6 to 25 carbon atoms and is bound to a silicon atom, and a molar ratio of the aryl groups in the silicon compound with respect to the silicon atoms in the silicon compound is from 0.4 to 1.5.
 11. The curable composition of claim 1, wherein the silicon compound has a viscosity at 25° C. of 1,000 cP or less.
 12. The curable composition of claim 1, wherein the silicon compound has a weight average molecular weight of less than 1,000.
 13. The curable composition of claim 1, wherein the silicon compound comprises a unit represented by the following Formula 4: H_(a)Y_(b)SiO_((4-a-b)/2)  [Formula 4] wherein Y represents a monovalent hydrocarbon group having 1 to 25 carbon atoms, a is in a range of 0.3 to 1, and b is in a range of 0.9 to
 2. 14. The curable composition of claim 1, wherein the silicon compound is comprised in an amount of 10 to 500 parts by weight, relative to 100 parts by weight of the mixture of the linear polysiloxane and the oligomeric compound.
 15. The curable composition of claim 1, further comprising a cross-linked polysiloxane represented by an average composition equation of the following Formula 5: (R⁵R⁶R⁷SiO_(1/2))_(c)(R⁸R⁹SiO_(2/2))_(d)(R¹⁰SiO_(3/2))_(e)(SiO_(4/2))_(f)  [Formula 5] wherein R⁵ to R¹⁰ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, an epoxy group, an alkenyl group having 2 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms, provided that, when each of R⁵ to R¹⁰ is present in plural numbers, each of R⁵ to R¹⁰ may be the same as or different from each other, and at least one of R⁵ to R¹⁰ is an alkenyl group having 2 to 20 carbon atoms, and provided that, when c+d+e+f is set to 1, c is in a range of 0 to 0.5, d is in a range of 0 to 0.3, e is in a range of 0 to 0.8, and f is in a range of 0 to 0.2, provided that e and f are not 0 at the same time.
 16. A semiconductor device encapsulated by an encapsulation material comprising a cured product of the curable composition defined in claim
 1. 17. A light emitting diode encapsulated by an encapsulation material comprising a cured product of the curable composition defined in claim
 1. 18. A liquid crystal display device comprising the light emitting diode defined in claim 17 as a light source.
 19. A lighting device comprising the light emitting diode defined in claim
 17. 